I want to commend you on your choice of carseat. Britax is by far the best in safety seats for childre. I own a Britax Maratho,n roundabout a star rise booster, and a graco snugride (unfortunately i couldn't see spending 200 on an infant carrier which would be used for uch a short time). I'm SO glad I found this thread. I am looking to take in one daycare child along with my 2 year old and 1 month old and was wanting to make sure I could fit in my kids marathon, roundabout and a third carseat (probably graco comfortsport or cosco touriva, since it's the slimmest seat) Can I ask you the arrangement of your seats to get the best fit?